1. Field of the Invention
Exemplary aspects of the present invention generally relate to a document feeder, a method for controlling the document feeder, and a recording medium storing a control program for causing a data processing device to execute the method for controlling the document feeder, and more particularly, to a document feeder capable of automatically reversing a document.
2. Description of the Background
Related-art image reading devices such as copiers and scanners generally include an automatic document feeder (ADF) to separate a stack of documents placed on a document stand from one another and convey the documents one by one to a position at which the documents are copied or scanned. In order for the copy or scan to be successful, the document must not be tilted or otherwise askew when copied or scanned.
A variety of mechanisms to correct a tilt of a document conveyed through a conveyance path in the ADF relative to a direction of conveyance of the document, that is, skew of the document, have been proposed. For example, Published Unexamined Japanese Patent Application No. 2000-313548 (hereinafter referred to as JP-2000-313548-A) discloses an ADF in which a document is struck against a striking roller provided along the conveyance path and bent to correct skew of the document.
In the ADF disclosed in JP-2000-313548-A, a force with which the document is struck against the striking roller is adjustable, thereby accurately correcting the skew of the document depending on characteristics of the document paper as well as mechanical tolerances of each device.
However, a large number of constituent components are required for the related-art ADFs in order to perform such skew correction, causing cost increase. For example, in an arrangement in which the document is bent by being struck against the striking roller to correct the skew of the document as described above, rotation of the striking roller is stopped while the roller is being struck by the document, and the striking roller is then rotatively driven to convey the document after the document is bent and the skew of the document is corrected. In such a case, the striking roller and a drive mechanism to drive the striking roller are required, increasing the number of components of the ADF.
The conveyance path in the ADF is partially defined by one or more sets of conveyance rollers. If a conveyance roller provided along the conveyance path to convey the document is also made to function as the striking roller, it is not necessary to provide an independent striking roller to the ADF. However, a mechanism to control rotation of the conveyance roller is additionally required to cause the conveyance roller to also function as the striking roller, leaving the problem of cost increase unresolved.